This paper describes further work on XP-8843, a novel Advanced Negative Resist (ANR) system developed specifically for Kr-F excimer laser and broadband DUV advanced imaging systems. Optical changes in the resist film have been measured for exposed and post-exposure baked samples. At lithographically useful doses, 10mJ/cm2, virtually no change in % transmittance occurs upon exposure. The post-exposure bake at 130°C leads to slight darkening (62 to 54%T). Resist modelling studies have shown that 10-6 moles of acid per gram of resist are necessary to induce sufficient crosslinking to decrease resist dissolution rate in aqueous base by fifty-fold. Based on the concentration of acid, the average distance between nearest acid neighbors is 100Å in the exposed film. Contrast curves were generated on a 0.35 NA GCA ALS LaserstepTM 200 5:1 stepper. Contrast was as high as 6 at 130°C post-exposure bake. Arrhenius plots of XP-8843 and the poly(p-vinyl)phenol-modelled resist vs. post-exposure bake temperature both gave Ea of 43kJ/mole. The XP-8843 resist exhibited high resolution (0.45 micron 1/s pairs) and vertical sidewalls when imaged at 1.35 micron thickness. The XP-8843 resist also shows high thermal resistance, maintaining linewidth at 210°C.
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Thackeray et al. (1989) studied this question.